With the prospect of three civil wars looming over the Middle East — and Iran poised to gain from them all — Saudi Arabia has abandoned its behind-the-scenes checkbook diplomacy and taken on a central, aggressive role in reshaping the region’s conflicts.

On Tuesday, the kingdom is playing host in Mecca to the leaders of Hamas and Fatah, the two feuding Palestinian factions, in what both sides say could lead to a national unity government and reduced bloodshed. Last fall, senior Saudi officials met secretly with Israeli leaders about how to establish a Palestinian state.

In recent months, Saudi Arabia has also increased its public involvement in Iraq and its support of the Sunni-led government in Lebanon. The process is shaping up as a counteroffensive to efforts by Iran to establish itself as the regional superpower, according to diplomats, analysts and officials here and throughout the region. Some even say that the recent Saudi commitment to temper the price of oil is aimed at undermining Iran’s economy, although officials here deny that.

“We realized that we have to wake up,” said a high-ranking Saudi diplomat who spoke on the condition of anonymity because he was not authorized to speak to the news media. “Someone rang the bell, ‘Be careful, something is moving.”’

The shift is occurring with encouragement from the Bush administration. Its goal is to see an American-backed alliance of Sunni Arab states including Saudi Arabia, Jordan, Lebanon and Egypt, along with a Fatah-led Palestine and Israel, opposing Iran, Syria and the radical groups they support.

Yet Riyadh’s goals may not always be in alignment with those of the White House, and could complicate American interests.

The Saudi effort has been taken in collaboration with its traditional Persian Gulf allies and Egypt and Jordan, but it also represents another significant shift in a region undergoing a profound reshuffling. The changes are linked to the toppling of Saddam Hussein and the transfer of power from Sunni Muslims to Shiites in Iraq, analysts said. They also reach back many years to the gradual decline in influence of Cairo and the collapse of a pan-Arab agenda, analysts and diplomats said.

“The Saudis felt that the Iranian role in the region has become influential, especially in Iraq, Palestine and Lebanon, and that the Iranian role was undermining their role in the region,” said Muhammad al-Sakr, head of the foreign affairs committee in Kuwait’s Parliament. “Usually the Saudis prefer to maneuver behind the scenes,” he said. “Lately they’ve been noticeably active.”

Saudi Arabia has taken public initiatives in the past, including one in 2002, when at an Arab League meeting it proposed a regional peace agreement with Israel in exchange for Israel’s withdrawing to its 1967 boundaries. But it prefers to work quietly, and has not recently taken such a sustained public posture.

“This is not leadership by choice, it is leadership by necessity,” said Gamal Abdel Gawad, an expert at the Ahram Center for Political and Strategic Studies in Cairo.